Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 2,835	$ (1,739)	$ 9,287	$ (2,074)
Foreign currency translation adjustment	796	318	1,337	(623)
Comprehensive income (loss)	3,631	(1,421)	10,624	(2,697)
Comprehensive loss attributable to noncontrolling interest	0	293	0	668
Comprehensive income (loss) attributable to Amtech Systems, Inc.	$ 3,631	$ (1,128)	$ 10,624	$ (2,029)